1. Field of the Invention
The present invention relates to a friction resistance generator which is used as a mechanism for providing the rotational motion of various types of machines with an arbitrary resistance due to a frictional force.
2. Description of the Related Art
Generally, bearings known as one of machine elements are broadly classified into sliding bearings for supporting a member on the shaft side via a lubricating oil and rolling bearings for supporting a member on the shaft side via balls or rollers. For all of these bearings, the frictional resistance between the members is minimized because the object thereof is to allow the member on the shaft side to always move smoothly. Because the bearing is not intended to control the power by providing the moving member with a resistance, a damping device such as a shock absorber or a damper is provided additionally when it is desired to control the rotational speed to be constant as in case of an automatic door closing mechanism.
Also, mechanisms such as a clutch, a torque limiter, or a brake are known as a mechanism for generating sliding friction between two rotating members. The object of these mechanisms is not only to completely stick with pressure the members but also to transmit power while producing a difference in rotation according to the load between the members by utilizing the sliding friction.
The sliding bearing described above can be operated with a very low frictional resistance equivalent to that of the rolling bearing if the lubricating oil is interposed between the members in an ideal state. However, it is very difficult to supply a lubricating oil always in an ideal state. Therefore, the sliding bearing has a disadvantage that two sliding surfaces sometimes come into direct contact with each other, thereby remarkably increasing the frictional force. Also, for a rotating mechanism using a bearing, the only method for controlling the rotational speed to be constant is to additionally provide an expensive damping device, which leads to a problem in that the cost increases and the construction becomes complicated and large.
Further, for a mechanism for transmitting power by utilizing sliding friction as in case of a clutch, it is very difficult to control a frictional force in a semi-contact state to be constant. Especially when one member rotates at a lower speed with respect to the other member, a problem occurs in that a so-called stick slip easily occurs, in which static friction and dynamic friction act intermittently on the two sliding surfaces, whereby the frictional force becomes extremely unstable.
Thereupon, the inventor of the present invention has already proposed a friction resistance generator which can control the speed of rotating motion of an object to be constant without additionally providing a special mechanism, can carry out the control easily, and can always generate a stable frictional force, the apparatus having been disclosed in Japanese Patent Nos. 2733200 and 2801153.
The invention disclosed in Japanese Patent No. 2801153 provides a rolling friction apparatus comprising a rotary member rotating around the axis, a number of rollers arranged along the rotation path of the rotary member, a passive member facing the rotary member in the radial direction with the rollers interposed therebetween, and a cage for rotatably holding the rollers at intervals, wherein the opposed surfaces of the rotary member and the passive member are formed so as to be parallel with the rotation axis of the rotary member, and the rolling axis of each of the rollers is inclined so as to make a predetermined angle with respect to a cross section including the rotation axis of the rotary member. Specifically, in this rolling friction apparatus, at least one of the rotary member and the passive member is pressed by applying an arbitrary load onto the roller side and the rotary member is rotated, by which the rollers are rolled while being accompanied with sliding friction, so that a stable frictional force can be generated.
However, in the rolling friction apparatus, the opposed surfaces of the rotary member and the passive member must be flat surfaces parallel to each other or surfaces having a symmetrical shape because the inclined rollers roll while being in contact with the opposed surfaces of the rotary member and the passive member. Therefore, when the rotary member and the passive member are formed by a cylindrical or spherical member opposing in the radial direction, the rollers cannot be brought into uniform contact with the surfaces of both the rotary member and the passive member, so that there remains a problem in that it is difficult to apply this invention to the apparatus using the rotary member and the passive member having the opposed surfaces of such a curved shape.
The present invention has been made to solve the above problems, and accordingly an object thereof is to provide a friction resistance generator capable of always generating a stable frictional force even if the opposed surfaces of a rotary member and a passive member have a curved shape such as a circumferential surface or a spherical surface.
The present invention provides a friction resistance generator comprising a rotary member rotatable in a predetermined direction, a passive member arranged so as to be opposed to a predetermined surface of the rotary member, and a number of rollers arranged at intervals in a predetermined direction between the opposed surfaces of the rotary member and the passive member, the rotation axis of each of the rollers being inclined at a predetermined angle with respect to the rotation direction of the rotary member, wherein the opposed surfaces of the rotary member and the passive member are formed into a predetermined curved shape, the rollers are installed rotatably on either one of the opposed surfaces of the rotary member and the passive members, and the rollers are arranged so as to be contactable with the other of the opposed surfaces of the rotary member and the passive member.
Thereupon, when the rotary member is rotated in the predetermined direction while a load is applied to the passive member, the rollers supported rotatably on one of the rotary member and the passive member rotate while being in contact with the rotary member or the passive member. In this case, even if the opposed surfaces of a rotary member and a passive member have a curved shape such as a circumferential surface or a spherical surface, the rollers can be formed so as to rotate while being in contact with only either one of the rotary member and the passive member. Also, since the roller is rotatably supported on the rotary member or the passive member, the roller rotates while rolling motion thereof in a direction inclined at a predetermined angle with respect to the rotation direction of the rotary member is regulated. Thereby, a frictional force according to the load is generated between the roller and the rotary member or the passive member. At this time, the roller produces sliding friction while rotating, so that less static friction is produced even at the time of low-speed rotation, whereby a stable resisting force can always be provided.
Also, in the above configuration, the rotary member and the passive member are formed into a cylindrical shape, and are arranged coaxially with each other, a plurality of roller trains are provided in the axial direction of the rotary member, and the rotary member is movably provided in the axial direction so that only an arbitrary roller train comes into contact with the rotary member or the passive member. Thereby, an arbitrary frictional force can be provided depending on the axial position of the rotary member.
Further, the opposed surfaces of the rotary member and the passive member are formed into a spherical shape, and the rotary member and the passive member are concentrically arranged. Also, the rotary member is rotatably connected to a foundation structure of an arbitrary building, and the passive member is fixed to the ground. Thereby, the apparatus can be caused to function as a seismic isolation device for a building.